Radiation Embrittlement of Cr–Ni–Mo and Cr–Mo RPV Steels

Radiation embrittlement kinetics of Cr–Mo and Cr–Ni–Mo steels, used for manufacturing VVER-440 and VVER-1000 RPV steels, respectively, are under consideration. Radiation embrittlement of VVER-440 and VVER-1000 RPV steels exposed to irradiation for 17–22 years is analyzed. Extremely high levels of thermal aging of VVER-1000 RPV steels at 320°C is pointed out. The neutron flux effect problem and the problem of accelerated radiation embrittlement of welds with high nickel contents are emphasized. The effect of phosphorus, copper, silicon, manganese, and nickel contents on radiation embrittlement of VVER-440 and VVER-1000 RPV steels is studied using the Russian surveillance database and representative results of research programs. The trend curves for VVER-440 and VVER-1000 RPV steels are proposed. The mechanisms of radiation embrittlement of Cr–Ni–Mo and Cr–Mo RPV steels are supposed.